National Park Service U.S. Department of the Interior State of the Park Report Zion National Park Utah 2016 National Park Service. 2016. State of the Park Report for Zion National Park. State of the Park Series No. 23. National Park Service, Washington, DC. On the cover: Visitors enjoy the cultural landscape setting at the Zion Lodge beneath the natural splendor of the Mountain of the Sun in Zion Canyon. Disclaimer. This State of the Park report summarizes the current condition of park resources, visitor experience, and park infrastructure as assessed by a combination of available factual information and the expert opinion and professional judgment of park staff and subject matter experts. The internet version of this report provides the associated workshop summary report and additional details and sources of information about the findings summarized in the report, including references, accounts on the origin and quality of the data, and the methods and analytic approaches used in data collection and assessments of condition. This report provides evaluations of status and trends based on interpretation by NPS scientists and managers of both quantitative and non- quantitative assessments and observations. Future condition ratings may differ from findings in this report as new data and knowledge become available. The park superintendent approved the publication of this report. Executive Summary The mission of the National Park Service is to preserve unimpaired the natural and cultural resources and values of national parks for the enjoyment, education, and inspiration of this and future generations. NPS Management Policies (2006) state that “The Service will also strive to ensure that park resources and values are passed on to future generations in a condition that is as good as, or better than, the conditions that exist today.” As part of the stewardship of national parks for the American people, the NPS has begun to develop State of the Park reports to assess the overall status and trends of each park’s resources. The NPS will use this information to improve park priority setting and to synthesize and communicate complex park condition information to the public in a clear and simple way. The purpose of this State of the Park report is to: • Provide to visitors and the American public a snapshot of the status and trend in the condition of a park’s priority resources and values; • Summarize and communicate complex scientific, scholarly, and park operations factual information and expert opinion using non-technical language and a visual format; • Highlight park stewardship activities and accomplishments to maintain or improve the State of the Park; • Identify key issues and challenges facing the park to help inform park management planning. The purpose of Zion National Park (ZION) is to preserve the dramatic geology including Zion Canyon and a labyrinth of deep and brilliantly colored Navajo sandstone canyons formed by extraordinary processes of erosion at the margin of the Colorado Plateau; to safeguard the park’s wilderness character and its wild and scenic river values; to protect evidence of human history; and to provide for scientific research and the enjoyment and enlightenment of the public. Significance statements express why ZION resources and values are important enough to merit national park unit designation. Statements of significance describe why an area is important within a global, national, regional, and systemwide context. These statements are linked to the purpose of the park unit, and are supported by data, research, and consensus. Significance statements describe the distinctive nature of the park and inform management decisions, focusing efforts on preserving and protecting the most important resources and values of the park unit. ZION is significant because: • ZION is a geologic showcase of brilliantly colored strata highlighted by sheer Navajo sandstone cliffs that are among the highest in the world and expose ancient remnants of the largest known sand dune system. Geologic processes continue today as the free-flowing Virgin River rapidly cuts into the margin of the Colorado Plateau, incising a multitude of deep, narrow canyons. An abundance of canyon springs, fed by groundwater, create hanging gardens and grottos that support endemic varieties of flora and fauna. These exceptional features and processes contribute to the outstanding scenery and scientific value of the park. • The range of topography in ZION and location at the juncture of the Colorado Plateau, Mojave Desert, and Great Basin ecoregions have created the environment for a wide variety of life forms, including rare and endemic species that exist only in this small geographic area. This diversity of life forms provides opportunities for valuable scientific research. • The Zion Wilderness preserves the undeveloped character and natural environment of the spectacular network of colorful deep sandstone canyons, high forested plateaus, and striking rock towers, as well as opportunities for visitors to experience a strong sense of solitude and remoteness from civilization. • Utah’s first designated wild and scenic rivers flow through the park carving a colorful labyrinth of canyons across layers of time. These rivers, fed by natural undiminished spring flows from the Navajo sandstone aquifers and sculpted by unimpeded torrents of flood waters, have an ecological value that far exceeds their spatial extent in the park. • In a canyon environment, ZION preserves human history of the Ancestral Puebloan, Paiute, pioneers, early 20th-century tourism, and NPS development along the Virgin River. The remarkable integrity of these resources provides a setting ideal for future education and research. • ZION is a world-renowned destination that offers opportunities for a range of recreational and educational experiences including passive activities and high adventure excursions. Visitors are able to step inside the scenery and can find themselves surrounded by narrow cliff walls in places of extraordinary scale such as the Virgin River Narrows. These experiences often create profound emotional and personal connections for a diversity of visitors. The summary table, below, and the supporting information that follows, provide an overall assessment of the condition of priority resources and values at ZION based on scientific and scholarly studies and expert opinion. The internet version of this report, available at http://www.nps.gov/stateoftheparks/zion/, provides additional detail and sources of information about the resources State of the Park Report iii Zion National Park summarized in this report, including references, accounts on the origin and quality of the data, and the methods and analytical approaches used in the assessments. Reference conditions that represent “healthy” ecosystem parameters, and regulatory standards (such as those related to air or water quality) provide the rationale to describe current resource status. In coming years, rapidly evolving information regarding climate change and associated effects will inform our goals for managing park resources, and may alter how we measure the trend in condition of park resources. Thus, reference conditions, regulatory standards, and/or our judgment about resource status or trend may evolve as the rate of climate change accelerates and we respond to novel conditions. In this context, the status and trends documented here provide a useful point-in-time baseline to inform our understanding of emerging change, as well as a synthesis to share as we build broader climate change response strategies with partners. The Status and Trend symbols used in the summary table below and throughout this report are summarized in the following key. The background color represents the current condition status, the direction of the arrow summarizes the trend in condition, and the thickness of the outside line represents the degree of confidence in the assessment. In some cases, the arrow is omitted because data are not sufficient for calculating a trend (e.g., data from a one-time inventory or insufficient sample size). Confidence in Condition Status Trend in Condition Assessment Warrants Condition is Improving High Significant Concern Warrants Condition is Unchanging Medium Moderate Concern Resource is in Good Condition is Deteriorating Low Condition State of the Park Summary Table Condition Priority Resource or Value Rationale Status/Trend Natural Resources web Vistas at ZION are at times obscured by pollution-caused haze. Ozone sometimes reaches levels that can make breathing difficult for sensitive groups and cause injury to ozone-sensitive plants. Arid ecosystems and grasslands are particularly vulnerable to changes caused by nitrogen deposition. Interactions Air Quality between nitrogen, invasive exotic annual grasses, and fire have implications for changes to biodiversity in non-fire adapted areas of the park. Airborne toxics, including mercury, can deposit with rain and snow and accumulate in organisms, such as fish and birds. A recent study found elevated mercury levels in small prey fish (speckled dace) at ZION. Geologic features and processes, including soils, are in substantially natural condition and function. Exceptions include the relatively small developed portions of the park, and stream channelization in Zion Canyon. The status Geologic Features would be scored as green except for the large number of geologic hazards always and Processes present in the park that pose a threat to all facilities,